I love the physical puzzles. One thing that frustrated me about Saira was that, as much as I loved the atmosphere and graphics, the puzzles usually had nothing to do with the level itself (i.e. you come to a computer terminal and solve some maze) and the difficulty of those puzzles, while being unrelated to the levels themselves, is the one major reason I haven't replayed Saira. In NightSky, on the contrary, the puzzles have to do with navigating the screens themselves. Hooray for physics puzzles!
I also really like the music. It's more electronic-ambient than I was expecting, as I downloaded a Chris Schlarb album a while back and it sounded more acoustic. Also, one of the tracks early in the game REALLY reminds me of the Dragon Noir music in Saira. Like, to the point that I almost think it's the same music (though, as I said above, I only played Saira once, so I can't be too sure.) It seems to me that Chris Schlarb (if he actually did all the music for this game, which is my understanding) really studied the music in previous Nifflas games and was heavily influenced by it on this soundtrack. And I think that's a good thing.